The NFL lockout is finally over and we can all stop pretending to care about soccer. It's time to revel at the altar of America's Sport in the Mecca of Texas under the world's largest single-span retractable roof.
Cowboys Stadium is $US1.5 billion worth of huge — like 214,000sqm, 80,000-fan seating capacity sort of huge. You could fit the whole of the American Airlines Center in at field level and stand The Statue of Liberty on the 50-yard line with the roof closed. It's so big, I'm pretty sure it's visible from Cleveland on a clear day. And since everything must be bigger in Texas (per state law), the stadium designers capped it with a 61,000sqm roof.
The roof itself was designed by the Walter P Moore structural engineering firm and produced by Uni-Systems. The 61,000sqm roof is supported by two 5m x 11m arch box trusses spanning 373m. Its 12791-tonne structural steel skeleton (that's 282 Fin Whales or 92 Boeing 777s worth) is covered with a weather-resistant PVC membrane on its non-moving sections. Its movable bits, however, are what set it apart from lesser retractable-roof stadiums.
Two 91m x 67m panels are hoisted 66m up and down a 23.9-degree slope (the steepest movable-roof incline in North America) using an ingenious, custom rack-and-pinion track system. Instead of using one or two massive engines to shift 726,000kg of roof panel, designers employed a series of 64 separate 7.5hp motors embedded in 32 tractors. As the panels move down the side of the roof the motors are used counteract gravity's pull and, using regenerative drives, harness the power generated and fed into the stadium's power grid. The total 480hp fully opens or closes the 78m x 125m gap n just 12 minutes. Even when closed, the roof retains the the old Texas Stadium's trademark hole thanks to the panels' 13,700sqm of translucent, Teflon-coated, PTFE fibreglass membrane that is self-washing, impermeable to UV light, and can withstand temperatures from -73C to 232C (yes it does get that hot in Texas; they call it August).
The first opening of the roof (yes, that's the George Strait):
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